Preparation and Characterization of TiO₂ and SiO₂Thin Films

Abstract

Although scaling will continue for couple of decades but device geometries reaches to atomic size and limitation of quantum mechanical physical boundaries. To address these problems there is need of innovation in material science & engineering, device structure, and new nano devices based on different principle of physics. So TiO₂ thin films have been grown on well clean N-type silicon substrates via a sol–gel spin coating method. MOS capacitor were fabricated and characterized with SiO₂ and TiO₂ as dielectric material on N-type silicon wafer. The thickness was measured by stylus profiler and found to be 510 Å and 528 Å for SiO₂ and TiO₂ respectively. Some of the material parameters were found from the measured Capacitance -Voltage (C-V) curve obtained by SUPREM-III (Stanford University Process Engineering Model Version 0-83) for SiO₂ and C-V Keithly 590 analyzer for TiO₂ thin films. The result shows that obtained TiO₂ film present a dielectric constant of approximately 80. The refractive index was found to be 2.4 and optical constant was 5.43 obtained from Ellipsometry. Band gap 3.6 eV of TiO₂ was calculated by spectrophotometer and Surface morphology was obtained using Scanning Electron Microscope (SEM-JEOL) micrograph. The aluminum (Al) metal was deposited by the thermal evaporation system on the back side of the sample for the ohmic contact. Analysis shows that TiO₂ may be acceptable as a viable substitute for high k dielectric in order to prevent the tunneling current problems.